This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Purpose: The purpose of this study is to assess the level of fitness in asthmatic children and correlate this assessment with asthma severity and response to bronchodilator. Hypothesis: We hypothesize that decreased fitness levels in asthmatic children correlates with increasing asthma severity. SPECIFIC AIMS: Specific Aim 1: To determine the level of fitness in asthmatic children using a comprehensive and state-of-the-art approach through 1) an exercise challenge and 2) body composition, as assessed through a DEXA scan. Specific Aim 2: To determine subject asthma severity, based on NHLBI guidelines, as assessed through 1) pulmonary function testing 2) response to bronchodilator and 3) a questionnaire of asthma symptoms. Specific Aim 3: To assess the level of habitual physical activity in asthmatic children through validated, age appropriate surveys. Background: There is a growing body of literature that implicates lifestyle factors, in particular physical inactivity, as a contributor to the increase in asthma prevalence and severity. Indeed, numerous studies link body composition (obesity) to asthma. However, the level of fitness in asthmatics has been poorly assessed, particularly as correlated to asthma severity. This study proposes to study the fitness level of asthmatic children and correlate asthma severity levels to degree of fitness.